In recent years, in various fields, a computer system has served as an essential infrastructure system, and it has become much more important to cause the computer system to operate properly without bringing the computer system to a halt. Consequently, there has been developed various technologies for monitoring an operational status of a computer system to detect an abnormality of the system early.
For example, in a business system, since analyzing a transaction (a flow of a service process), a unit process, is useful for monitoring a processing status, there has been developed a technology of collecting a log of messages exchanged over a network for a service process and estimating a transaction based on a calling relationship among the messages in the log (see Japanese Laid-open Patent Publication No. 2006-11683). By using such a technology, many different types of transactions in the business system, including low-frequency ones, can be extracted without a human hand, and the analysis of the system can be assisted.
However, in the technology described in Japanese Laid-open Patent Publication No. 2006-11683, there is a problem that it is difficult to perceive the status of the whole system because an enormous number of types of transactions ranging from high-frequency ones to very low-frequency ones are created.